Oxidation process to produce a crude and/or purified carboxylic acid product

ABSTRACT

Disclosed is an oxidation process to produce a crude carboxylic acid product carboxylic acid product. The process comprises oxidizing a feed stream comprising at least one oxidizable compound to generate a crude carboxylic acid slurry comprising furan-2,5-dicarboxylic acid (FDCA) and compositions thereof. Also disclosed is a process to produce a dry purified carboxylic acid product by utilizing various purification methods on the crude carboxylic acid.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims priority to U.S. Provisional Application Ser.No. 61/489,488 filed May 24, 2011, the disclosures of which are hereinincorporated by reference in their entirety to the extent they do notcontradict the statements herein.

FIELD OF THE INVENTION

The present invention relates to a process to produce a carboxylic acidcomposition. The process comprises oxidizing at least one oxidizablecompound in an oxidizable raw material stream in the presence of anoxidizing gas stream, solvent stream, and at least one catalyst system.

More particularly, the present invention relates to a process to producea carboxylic acid composition comprising furan-2,5-dicarboxylic acid(FDCA) and compositions thereof. The process comprises oxidizing5-hydroxylmethyl)furfural in the presence of oxygen, a saturated organicacid solvent having from 2-6 carbon atoms, and a catalyst system at atemperature of about 100° C. to about 220° C. to produce the carboxylicacid composition comprising furan-2,5-dicarboxylic acid.

BACKGROUND OF THE INVENTION

Aromatic dicarboxylic acids, such as terephthalic acid and isophthalicacid, are used to produce a variety of polyester products. Importantexamples of which are poly (ethylene terephthalate) and its copolymers.These aromatic dicarboxylic acids are synthesized by the catalyticoxidation of the corresponding dialkyl aromatic compounds which areobtained from fossil fuels, which is disclosed in U.S. PatentApplication 2006/0205977 A1), which is herein incorporated by referenceto the extent it does not contradict the statements herein.

There is a growing interest in the use of renewable resources as feedstocks for the chemical industry mainly due to the progressive reductionof fossil reserves and their related environmental impacts.Furan-2,5-dicarboxylic acid (FDCA) is a versatile intermediateconsidered as a promising closest biobased alternative to terephthalicacid and isophthalic acid. Like aromatic diacids, FDCA can be condensedwith diols such as ethylene glycol to make polyester resins similar topolyethylene terephthalate (PET) (Gandini, A.; Silvestre, A. J; Neto, C.P.; Sousa, A. F.; Gomes, M. J. Poly. Sci. A 2009, 47, 295.). Therefore,there is a need in the chemical industry for an efficient process toproduce carboxylic acid compositions, especially FDCA. A high yieldprocess (minimum of 90% FDCA yield) to produce a dry, purified FDCAproduct is provided herein.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates different embodiments of the invention wherein aprocess to produce a dried purified carboxylic acid 710 is provided.

FIG. 2 illustrates an embodiment of the invention, showing the GCchromatogram of the carboxylic acid composition 110 that has been dried.

FIG. 3 illustrates an embodiment of the invention, showing a ¹H NMR ofthe carboxylic acid composition 110 that has been dried.

FIG. 4 illustrates an embodiment of the invention, showing a ¹³C{¹H} NMRof the carboxylic acid composition 110 that has been dried.

FIG. 5 illustrates an embodiment of the invention, showing the effectsof temperature, pressure, cobalt and bromine concentrations have on theFDCA yield in the carboxylic acid composition 110.

FIG. 6 illustrates an embodiment of the invention, Effect of temperatureon yield using an oxidizable raw material stream 30 comprising 5-AMF.The + symbol represents that Co is 2000 ppm and Br is 3000 ppm. The xsymbol represents that Co is 2500 ppm and Br is 2500 ppm.

FIG. 7 illustrates an embodiment of the invention, Effect of temperatureon yield using an oxidizable raw material stream 30 comprising 5-EMF.The + symbol represents that Co is 2000 ppm and Br is 3000 ppm. The xsymbol represents that Co is 2500 ppm and Br is 2500 ppm.

DETAILED DESCRIPTION

It should be understood that the following is not intended to be anexclusive list of defined terms. Other definitions may be provided inthe foregoing description, such as, for example, when accompanying theuse of a defined term in context.

As used herein, the terms “a,” “an,” and “the” mean one or more.

As used herein, the term “and/or,” when used in a list of two or moreitems, means that any one of the listed items can be employed by itselfor any combination of two or more of the listed items can be employed.For example, if a composition is described as containing components A,B, and/or C, the composition can contain A alone; B alone; C alone; Aand B in combination; A and C in combination, B and C in combination; orA, B, and C in combination.

As used herein, the terms “comprising,” “comprises,” and “comprise” areopen-ended transition terms used to transition from a subject recitedbefore the term to one or more elements recited after the term, wherethe element or elements listed after the transition term are notnecessarily the only elements that make up the subject.

As used herein, the terms “having,” “has,” and “have” have the sameopen-ended meaning as “comprising,” “comprises,” and “comprise” providedabove.

As used herein, the terms “including,” “includes,” and “include” havethe same open-ended meaning as “comprising,” “comprises,” and “comprise”provided above.

The present description uses numerical ranges to quantify certainparameters relating to the invention. It should be understood that whennumerical ranges are provided, such ranges are to be construed asproviding literal support for claim limitations that only recite thelower value of the range as well as claim limitations that only recitethe upper value of the range. For example, a disclosed numerical rangeof 10 to 100 provides literal support for a claim reciting “greater than10” (with no upper bounds) and a claim reciting “less than 100” (with nolower bounds).

The present description uses specific numerical values to quantifycertain parameters relating to the invention, where the specificnumerical values are not expressly part of a numerical range. It shouldbe understood that each specific numerical value provided herein is tobe construed as providing literal support for a broad, intermediate, andnarrow range. The broad range associated with each specific numericalvalue is the numerical value plus and minus 60 percent of the numericalvalue, rounded to two significant digits. The intermediate rangeassociated with each specific numerical value is the numerical valueplus and minus 30 percent of the numerical value, rounded to twosignificant digits. The narrow range associated with each specificnumerical value is the numerical value plus and minus 15 percent of thenumerical value, rounded to two significant digits. For example, if thespecification describes a specific temperature of 62° F., such adescription provides literal support for a broad numerical range of 25°F. to 99° F. (62° F.+/−37° F.), an intermediate numerical range of 43°F. to 81° F. (62° F.+/−19° F.), and a narrow numerical range of 53° F.to 71° F. (62° F.+/−9° F.). These broad, intermediate, and narrownumerical ranges should be applied not only to the specific values, butshould also be applied to differences between these specific values.Thus, if the specification describes a first pressure of 110 psia and asecond pressure of 48 psia (a difference of 62 psi), the broad,intermediate, and narrow ranges for the pressure difference betweenthese two streams would be 25 to 99 psi, 43 to 81 psi, and 53 to 71 psi,respectively.

In one embodiment of the invention, a process is provided to producecarboxylic acid composition and/or dry purified carboxylic acid 710comprising furan-2,5-dicarboxylic acid (FDCA). Embodiments of theprocess are represented in FIG. 1. The process comprises oxidizing atleast one oxidizable compound in an oxidizable raw material stream 30 inthe presence of an oxidizing gas stream 10, solvent stream 20, and atleast one catalyst system. The oxidizable raw material stream 30comprises at least one oxidizable compound suitable to produce acarboxylic acid composition 110 comprising FDCA. The amount of FDCA inthe carboxylic acid composition 110 can range from greater than 10 byweight percent in the carboxylic acid composition 110, greater than 20by weight percent in the carboxylic acid composition 110, greater than30 by weight percent in the carboxylic acid composition 110. Thecarboxylic acid composition 110 comprises FDCA and solvent.

In another embodiment of the invention, the process comprises oxidizingat least one oxidizable compound in an oxidizable raw material stream 30in the presence of an oxidizing gas stream 10, solvent stream 20, and atleast one catalyst system. The oxidizable raw material stream 30comprises at least one oxidizable compound selected from the groupconsisting of 5-(hydroxymethyl)furfural (5-HMF), 5-HMF esters(5-R(CO)OCH₂-furfural where R=alkyl, cycloalkyl and aryl), 5-HMF ethers(5-R′OCH₂-furfural, where R′=alkyl, cycloalkyl and aryl), 5-alkylfurfurals (5-R″-furfural, where R″=alkyl, cycloalkyl and aryl), mixedfeedstocks of 5-HMF and 5-HMF esters, mixed feedstocks of 5-HMF and5-HMF ethers, mixed feedstocks of 5-HMF and 5-alkyl furfurals togenerate a carboxylic acid composition comprising FDCA. The process canoptionally include removing impurities from the carboxylic acidcomposition 110 in a liquid displacement zone 225 to form a low impurityslurry stream 210. The low impurity slurry stream 210 can be furthertreated in a secondary oxidation zone 335 to produce a secondaryoxidation slurry stream 310 which can be routed to a crystallizationzone 425 to form a crystallized slurry stream 410. The crystallizedslurry stream 410 is cooled in a cooling zone 430 and the cooledcrystallized slurry stream 510 can be routed to a solid-liquidseparation zone 625 to generate a purified wet cake stream 610comprising FDCA that is dried in a drying zone 725 to generate a dried,purified carboxylic acid 710 comprising purified FDCA.

In one embodiment of the invention, a process is provided to produce adried, purified carboxylic acid 710 comprising dried, purifiedfuran-2,5-dicarboxylic acid (FDCA) and comprises the following steps:

Step (a) comprises oxidizing at least one oxidizable compound in anoxidizable raw material stream 30 in the presence of an oxidizing gasstream 10, solvent stream 20, and at least one catalyst system in aprimary oxidation zone 125 which comprises at least one primary oxidizerreactor to produce a carboxylic acid composition 110 comprisingfuran-2,5-dicarboxylic (FDCA); wherein the oxidizable raw materialstream 30 comprises at least one oxidizable compound selected from thegroup consisting of 5-(hydroxymethyl)furfural (5-HMF), 5-HMF esters(5-R(CO)OCH₂-furfural where R=alkyl, cycloalkyl and aryl), 5-HMF ethers(5-R′OCH₂-furfural, where R′=alkyl, cycloalkyl and aryl), 5-alkylfurfurals (5-R″-furfural, where R″=alkyl, cycloalkyl and aryl), mixedfeedstocks of 5-HMF and 5-HMF esters, mixed feedstocks of 5-HMF and5-HMF ethers, and mixed feedstocks of 5-HMF and 5-alkyl furfurals.Structures for the various oxidizable raw material compounds areoutlined below:

The 5-HMF or its derivatives are oxidized with elemental O₂ in amulti-step reactions, eqs 1 and 2, to form FDCA with 5-formylfuran-2-carboxylc acid (FFCA) as a key intermediate.

In one embodiment of this invention, streams routed to the primaryoxidation zone 125 comprises an oxidizing gas stream 10 comprisingoxygen and a solvent stream 20 comprising solvent, an oxidizable rawmaterial stream 30, and a catalyst system. Oxidizable raw materialstream 30 comprises a continuous liquid phase. In another embodiment ofthe invention, the oxidizable raw material stream 30, the oxidizing gasstream 10, the solvent stream 20 and the catalyst system can be fed tothe primary oxidization zone 125 as separate and individual streams orcombined in any combination prior to entering the primary oxidation zone125 wherein said feed streams may enter at a single location or inmultiple locations in the primary oxidization zone 125.

The carboxylic acid composition 110 comprises FDCA and FFCA. In anotherembodiment the FFCA in the carboxylic acid composition 110 ranges fromabout 0.1 wt % (weight percent) to about 4 wt % or 0.1 wt % to about 0.5wt %, or 0.1 wt % to about 1 wt %. In another embodiment of theinvention the carboxylic acid composition 110 comprises FDCA and FFCAand at least one of 2,5-diformylfuran in an amount ranging from 0 wt %to about 0.2 wt %, levulinic acid in an amount ranging from 0 wt % to0.5 wt %, succinic acid in an amount ranging from 0 wt % to 0.5 wt % andacetoxy acetic acid in an amount ranging from 0 wt % to 0.5 wt %.

In another embodiment of the invention the carboxylic acid composition110 comprises FDCA, FFCA and EFCA. In other embodiment of the inventionthe EFCA in the carboxylic acid composition 110 in an range from about0.05 wt % to 4 wt %, or about 1 wt % to 2 wt %.

The catalyst system comprises at least one catalyst suitable foroxidation. Any catalyst known in the art capable of oxidizing theoxidizable compound can be utilized. Example of suitable catalystscomprise at least one selected from, but are not limited to, cobalt,bromine and manganese compounds, which are soluble in the selectedoxidation solvent. In another embodiment of the invention, the catalystsystem comprises cobalt, manganese and bromine wherein the weight ratioof cobalt to manganese in the reaction mixture is from about 10 to about400 and the weight ratio of cobalt to bromine is from about 0.7 to about3.5.

The oxidizing gas stream comprises oxygen. Examples include, but are notlimited to, air and purified oxygen. The amount of oxygen in the primaryoxidation zone ranges from about 5 mole % to 45 mole %, 5 mole % to 60mole % 5 mole % to 80 mole %.

Suitable solvents include water and the aliphatic solvents. In anembodiment of the invention, the solvents are aliphatic carboxylic acidswhich include, but are not limited to, aqueous solutions of C₂ to C₆monocarboxylic acids, e.g., acetic acid, propionic acid, n-butyric acid,isobutyric acid, n-valeric acid, trimethylacetic acid, caprioic acid,and mixtures thereof. In another embodiment of the invention, thesolvent is volatile under the oxidation reaction conditions to allow itto be taken as an off-gas from the oxidation reactor. In yet anotherembodiment of the invention the solvent selected is also one in whichthe catalyst composition is soluble under the reaction conditions.

The most common solvent used for the oxidation is an aqueous acetic acidsolution, typically having a concentration of 80 to 99 wt. %. Inespecially preferred embodiments, the solvent comprises a mixture ofwater and acetic acid which has a water content of 0% to about 15% byweight. Additionally, a portion of the solvent feed to the primaryoxidation reactor may be obtained from a recycle stream obtained bydisplacing about 80 to 90% of the mother liquor taken from the crudereaction mixture stream discharged from the primary oxidation reactorwith fresh, wet acetic acid containing about 0 to 15% water.

Suitable solvents include, but are not limited to, aliphaticmono-carboxylic acids, preferably containing 2 to 6 carbon atoms andmixtures thereof and mixtures of these compounds with water. Examples ofaliphatic mono-carboxylic acids, include, but are not limited to aceticacid.

Generally, the oxidation temperature can vary from about 100° C. toabout 220° C. and from about 110° C. to about 160° C.

In another embodiment of the invention, a process is provided to producefuran-2,5-dicarboxylic acid (FDCA) in high yields by liquid phaseoxidation that minimizes solvent and starting material loss throughcarbon burn. The process comprises oxidizing at least one oxidizablecompound in an oxidizable raw material stream 30 in the presence of anoxidizing gas stream 10, solvent stream 20, and at least one catalystsystem in a primary oxidation zone 125; wherein the oxidizable compoundis at least one selected from the group consisting of H(C═O)—R—(C═O)H,HOH2C—R—(C═O)H, and 5-(hydroxymethyl)furfural (5-HMF). The oxidizablecompound can be oxidized in a solvent comprising acetic acid with orwithout the presence of water with oxygen in the presence of a catalystsystem comprising cobalt, manganese and bromine, wherein the weightratio of cobalt to manganese in the reaction mixture is from about 10 toabout 400 and the weight ratio of cobalt to bromine is from about 0.7 toabout 3.5. Such a catalyst system with improved Co:Mn ratio can lead tohigh yield of FDCA. In this process, the oxidation temperature can varyfrom about 100° C. to about 220° C., or another range from about 110° C.to about 160° C., which can minimize carbon burn. The cobaltconcentration of the catalyst can range from about 1000 ppm to about6000 ppm, and the amount of manganese from about 2 ppm to about 600 ppm,and the amount of bromine from about 300 ppm to about 4500 ppm withrespect to the total weight of the liquid in the reaction medium of theprimary oxidation zone 125. As used herein, process temperature is thetemperature of the reaction mixture within the primary oxidation zonewhere liquid is present as the continuous phase. The primary oxidizerreactor will typically be characterized by a lower section where gasbubbles are dispersed in a continuous liquid phase. Solids can also bepresent in the lower section. In the upper section of the primaryoxidizer, gas is in the continuous phase and entrained liquid drops canalso be present.

In various embodiments of the invention, the catalyst compositionsemployed in the processes of the invention comprise cobalt atoms,manganese atoms, and bromine atoms, supplied by any suitable means, asfurther described below. The catalyst composition is typically solublein the solvent under reaction conditions, or it is soluble in thereactants fed to the oxidation zone. Preferably, the catalystcomposition is soluble in the solvent at 40° C. and 1 atm, and issoluble in the solvent under the reaction conditions.

The cobalt atoms may be provided in ionic form as inorganic cobaltsalts, such as cobalt bromide, cobalt nitrate, or cobalt chloride, ororganic cobalt compounds such as cobalt salts of aliphatic or aromaticacids having 2-22 carbon atoms, including cobalt acetate, cobaltoctanoate, cobalt benzoate, cobalt acetylacetonate, and cobaltnaphthalate.

The oxidation state of cobalt when added as a compound to the reactionmixture is not limited, and includes both the +2 and +3 oxidationstates.

The manganese atoms may be provided as one or more inorganic manganesesalts, such as manganese borates, manganese halides, manganese nitrates,or organometallic manganese compounds such as the manganese salts oflower aliphatic carboxylic acids, including manganese acetate, andmanganese salts of beta-diketonates, including manganeseacetylacetonate.

The bromine component may be added as elemental bromine, in combinedform, or as an anion. Suitable sources of bromine include hydrobromicacid, sodium bromide, ammonium bromide, potassium bromide, andtetrabromoethane. Hydrobromic acid, or sodium bromide may be preferredbromine sources.

In another embodiment of the invention, a process is provided forproducing furan-2,5-dicarboxylic acid (FDCA) in high yields by liquidphase oxidation that minimizes solvent and starting material lossthrough carbon burn. The process comprises oxidizing at least oneoxidizable compound in an oxidizable raw material stream 30 in thepresence of an oxidizing gas stream 10, solvent stream 20, and at leastone catalyst system in a primary oxidation zone 125; wherein theoxidizable compound is selected from the group consisting of5-(acetoxymethyl)furfural (5-AMF), 5-(ethoxymethyl)furfural (5-EMF),5-methyl furfural (5-MF); wherein the solvent stream 20 comprises aceticacid with or without the presence of water; wherein the catalyst systemcomprising cobalt, manganese and bromine, wherein the weight ratio ofcobalt to manganese in the reaction mixture ranges from about 10 toabout 400 and the weight ratio of cobalt to bromine is from about 0.7 toabout 3.5. The catalyst system with improved Co:Mn ratio can lead tohigh yield of FDCA. In this process, the oxidation temperature can varyfrom about 100° C. to about 220° C., or from about 110° C. to about 160°C. to minimize carbon burn. The cobalt concentration in the catalystsystem can range from about 500 ppm to about 6000 ppm, and the amount ofmanganese from about 2 ppm to about 600 ppm and the amount of brominefrom about 300 ppm to about 4500 ppm with respect to the total weight ofthe liquid in the reaction medium. Mixed feedstocks of 5-AMF and 5-HMFor 5-EMF and 5-HMF or 5-MF and 5-HMF or 5-AMF, 5-EMF and 5-HMF, withvarying ratios of the components can be used and similar results can beobtained.

In another embodiment of the invention, a process is provided forproducing furan-2,5-dicarboxylic acid (FDCA) in high yields by liquidphase oxidation that minimizes solvent and starting material lossthrough carbon burn. The process comprises oxidizing at least oneoxidizable compound in an oxidizable raw material stream 30 in thepresence of an oxidizing gas stream 10, solvent stream 20, and at leastone catalyst system in a primary oxidation zone 125; wherein saidoxidizable compound is 5-(hydroxymethyl)furfural (5-HMF); wherein saidsolvent stream comprises acetic acid with or without the presence ofwater; wherein said catalyst system comprising cobalt, manganese andbromine, wherein the weight ratio of cobalt to manganese in the reactionmixture is from about 10 to about 400. In this process, the temperaturecan vary from about 100° C. to about 220° C., from about 105° C. toabout 180° C., and from about 110° C. to about 160° C. The cobaltconcentration of the catalyst system can range from about 1000 ppm toabout 6000 ppm, and the amount of manganese can range from about 2 ppmto about 600 ppm, and the amount of bromine can range from about 300 ppmto about 4500 ppm with respect to the total weight of the liquid in thereaction medium.

In another embodiment of the invention, the process comprises oxidizingat least one oxidizable compound in an oxidizable raw material stream 30in the presence of an oxidizing gas stream 10, solvent stream 20, and atleast one catalyst system in a primary oxidation zone 125; wherein saidoxidizable compound is 5-(hydroxymethyl)furfural (5-HMF); wherein saidsolvent stream comprises a saturated organic acid having from 2-6 carbonatoms with or without the presence of water at a temperature of 100° C.to 220° C. to produce a dicarboxylic acid composition; wherein theprimary oxidation zone 125 comprises at least one primary oxidationreactor and wherein the catalyst system comprises cobalt in a range fromabout 500 ppm by weight to about 6000 ppm by weight with respect to theweight of the liquid in the reaction medium, manganese in an amountranging from about 2 ppm by weight to about 600 ppm by weight withrespect to the weight of the liquid in the reaction medium and brominein an amount ranging from about 300 ppm by weight to about 4500 ppm byweight with respect to the weight of the liquid in the reaction medium.

In another embodiment of the invention, when the oxidizable raw materialstream 30 comprises 5-HMF, then the cobalt to manganese ratio by weightis at least 10:1, 15:1, 20:1, 25:1, 30:1, 40:1, 50:1, 60:1, or 400 to 1.

In another embodiment of the invention, when the oxidizable materialstream 30 comprises at least one oxidizable compound selected from thegroup consisting of 5-HMF esters (5-R(CO)OCH₂-furfural where R=alkyl,cycloalkyl and aryl), 5-HMF ethers (5-R′OCH₂-furfural, where R′=alkyl,cycloalkyl and aryl), 5-alkyl furfurals (5-R″-furfural, where R″=alkyl,cycloalkyl and aryl), mixed feedstocks of 5-HMF and 5-HMF esters, mixedfeedstocks of 5-HMF and 5-HMF ethers, and mixed feed-stocks of 5-HMF and5-alkyl furfurals, the cobalt to manganese ratio by weight of thecatalyst system is at least 1:1, 10:1, 20:1, 50:1, 100:1, or 400:1.

In another embodiment of this invention, furan-2,5-dicarboxylic acid(FDCA) can be obtained by liquid phase oxidation of5-(hydroxymethyl)furfural (5-HMF), 5-(acetoxymethyl)furfural (5-AMF) and5-(ethoxymethyl)furfural (5-EMF) with molecular oxygen using Co/Mn/Brcatalyst system in acetic acid solvent. After the oxidation of5-HMF/5-AMF/5-EMF in presence of acetic acid, the FDCA precipitates outof solution. After filtration, washing with acetic acid and then withwater, and drying, solids were obtained with a minimum of 90%, 92%, 94%,96% FDCA content by weight.

In another embodiment of the invention, FDCA is obtained by liquid phaseoxidation of 5-HMF, 5-AMF and 5-EMF with molecular oxygen using Co/Mn/Brcatalyst system in acetic acid solvent. After the oxidation of5-HMF/5-AMF/5-EMF in acetic acid, the FDCA precipitates out of solution.After filtration, washing with acetic acid and then with water, anddrying, solids were obtained with a minimum of 96% FDCA content and amaximum b* of 15, 16, 17, 18, 19, or 20.

The b* is one of the three-color attributes measured on a spectroscopicreflectance-based instrument. The color can be measured by any deviceknown in the art. A Hunter Ultrascan XE instrument is typically themeasuring device. Positive readings signify the degree of yellow (orabsorbance of blue), while negative readings signify the degree of blue(or absorbance of yellow).

In another embodiment of the invention, a process is provided forproducing furan-2,5-dicarboxylic acid (FDCA) in minimum yields of 80% or85% or 90% or greater by liquid phase oxidation that minimizes solventand starting material loss through carbon burn. As used herein, yield isdefined as mass of FDCA obtained divided by the theoretical amount ofFDCA that should be produced based on the amount of raw material use.For example, if one mole or 126.11 grams of 5-HMF are oxidized, it wouldtheoretically generate one mole or 156.01 grams of FDCA. If for example,the actual amount of FDCA formed is only 150 grams, the yield for thisreaction is calculated to be =(150/156.01) times 100, which equals ayield of 96%. The same calculation applies for oxidation reactionconducted using 5-HMF derivatives or mixed feeds.

In another embodiment of this invention, a process is providedcomprising oxidizing at least one oxidizable compound in an oxidizableraw material stream 30 in the presence of an oxidizing gas stream 10,solvent stream 20, and at least one catalyst system in a primaryoxidation zone 125; wherein said oxidizable compound is selected fromthe group consisting of H(C═O)—R—(C═O)H, HOH2C—R—(C═O)H,5-(hydroxymethyl)furfural (5-HMF); wherein said solvent stream comprisesacetic acid with or without the presence of water; wherein said catalystsystem comprises cobalt, manganese and bromine, wherein the weight ratioof cobalt to manganese in the reaction mixture is from about 10 to about400 and the weight ratio of cobalt to bromine is from about 0.7 to about3.5. Such a catalyst system with improved Co:Mn and Co:Br ratio can leadto high yield of FDCA (minimum of 90%), decrease in the formation ofimpurities (measured by b*) causing color in the downstreampolymerization process while keeping the amount of CO and CO₂ in theoff-gas at a minimum.

The temperature in the primary oxidation zone can range from about 100°C. to about 220° C., and can range from about 110° C. to about 160° C.or can range from about 105° C. to about 180° C. or about 100° C. toabout 200° C., or about 100° C. to about 190° C. One advantage of thedisclosed primary oxidation conditions is low carbon burn as illustratedin Table 1. Oxidizer off gas stream 120 is routed to the oxidizer offgas treatment zone 825 to generate an inert gas stream 810, liquidstream 820 comprising water, and a recovered solvent stream 830comprising condensed solvent. In one embodiment, at least a portion ofrecovered solvent stream 830 is routed to wash fed stream 620 and thecombined stream is routed to the solid-liquid separation zone 625 forthe purpose of washing the solids present in the solid-liquid separationzone 625. In one embodiment, the inert gas stream 810 can be vented tothe atmosphere. In another embodiment, at least a portion of the inertgas stream 810 can be used as an inert gas in the process for inertingvessels and or used for conveying gas for solids in the process.

In another embodiment of the invention, the composition of the liquidphase within the primary oxidizer can have a pH from about −4.0 to about1.0 or the feedstock pH is from about −1.8 to about 1.0, or thefeedstock pH is from about −1.5 to about 1.0.

It should be understood that steps (b)-(g) are optional and only onepossible embodiment of a process to purified the carboxylic acidcomposition.

Step (b) comprises routing the crude carboxylic composition 110 andfresh solvent stream 220 to a liquid displacement zone 225 to produce adisplaced mother liquor stream 230 and low impurity slurry stream 210comprising FDCA. The displaced mother liquor stream 230 comprisessolvent and soluble matter dissolved in the solvent comprising dissolvedimpurities and dissolved catalyst. In various embodiments of theinvention, from about 5% to about 99%, from about 30% to about 90%, andmost preferably from about 50 to about 85% of mother liquor present inthe carboxylic acid composition 110 is displaced in the liquiddisplacement zone 225 resulting in dissolved matter comprisingimpurities present in the displaced mother liquor not going forward inthe process. Sufficient fresh solvent is fed to the liquid displacementzone 225 that becomes mixed with solids present resulting in a lowimpurity slurry stream 210 being pumpable with weight % solids rangingfrom 1% to 50%, 10% to 40%, and preferably the weight % solids in stream210 will range from 25% to 38%.

The liquid displacement zone may be a single unit operation or multipleunit operations. In one embodiment of the invention, the liquiddisplacement zone 225 may be any solid-liquid separation device capableof generating an isolated wet cake from a feed slurry and then mixingthe isolated wet cake with fresh solvent in a separate mixing device togenerate the low impurity slurry stream 210. Examples of suitablesolid-liquid separation devices include, but are not limited to, acontinuous pressure drum filter, solid bowl centrifuges including, butnot limited to, decanter and disc stack centrifuges, and batch pressurefilters including, but not limited to, candle and leaf filters. Thepreferred solid-liquid separation device for this application is acontinuous pressure drum filter. The solid-liquid separator is operatedat temperatures between about 30 degrees C. to about 200 degrees C.,preferably 80 degrees C. to about 170.degree. C. The solid-liquidseparator in the liquid displacement zone 225 may be operated incontinuous or batch mode, although it will be appreciated that forcommercial processes, the continuous mode is preferred. Alternatively, aportion of the mother liquor in stream 110 is displaced with freshliquor stream 220 in a single device to form the low impurity slurrystream 210 without forming an isolated wet cake.

In one embodiment, from 5% to 100% by weight of the displaced motherliquor stream 230 is routed to a purge zone 235 wherein a portion of theimpurities present in stream 230 are isolated and exit the process aspurge stream 920, wherein a portion is 5% by weight or greater.Recovered solvent stream 910 comprises solvent and catalyst isolatedfrom stream 230 and is recycled to the process. In one embodiment,recovered solvent stream 910 is recycled to the primary oxidation zone125 and contains greater than 30% of the catalyst that entered the purgezone 235 in stream 230. In another embodiment, stream 910 is recycled tothe primary oxidation zone 125 and contains greater than 50 weight %,contains greater than 70 weight %, and preferably greater than 90 weight% of the catalyst that enters the purge zone 235 in stream 230 on acontinuous or batch basis.

In another embodiment of this invention, a portion up to 100% of thecarboxylic acid composition 110 may be routed directly to a secondaryoxidation zone 335 without being subjected to the liquid displacementzone 225. In another embodiment of the invention, up to 100% of the feedto the purge zone 235 may be a mother liquor stream 630 generated in asolid-liquid separation zone 625 which also produces the purified wetcake stream 610.

In yet another embodiment, up to 100% of the feed to the purge zone 235may be mother liquor generated in a secondary liquid displacement zonelocated at some location downstream of the secondary oxidation zone 325.A secondary liquid displacement zone is not show in FIG. 1, and itcomprises equipment like that described for the liquid displacement zone225 located after the primary oxidation zone 125, and must be locatedafter the secondary oxidation zone 335.

Step (c) comprises oxidizing the low impurity slurry stream 210 in asecondary oxidation zone 335 to form a purified slurry stream 310. Inone embodiment of the invention, the low impurity slurry stream 210 isrouted to a secondary oxidation zone 335 where it is heated to betweenabout 115 degrees C. and about 220 degrees C., and preferably betweenabout 120 degrees C. to about 200 degrees C. and further oxidized withan oxidizing gas, such as air, fed by line 320 to produce a purifiedslurry stream 310. The secondary oxidation zone comprises at least oneoxidation reactor vessel. In one embodiment, the secondary oxidationzone can be one or more oxidation vessels. When the carboxylic acid inlow impurity slurry stream 210 is FDCA, the secondary oxidation zone isoperated at a temperature ranging from about 115 degrees C. to about 220degrees C., preferably between about 120 degrees C. to about 200 degreesC., and stream 210 is further oxidized with an oxidizing gas stream fedby line 320 to produce a purified slurry stream 310.

Generally, oxidation in the secondary oxidation zone 335 is at a highertemperature than the oxidation in the primary oxidation zone 125 toenhance the impurity removal. In one embodiment, the secondary oxidationzone 335 is operated at about 30° C., 20° C., and preferably 10° C.higher temperature than the oxidation temperature in the primaryoxidation zone 125 to enhance the impurity removal. The secondaryoxidation zone 335 can be heated directly with solvent vapor, or steamvia stream 320 or indirectly by any means known in the art.

Additional purification of the low impurity slurry stream 210 isaccomplished in the secondary oxidation zone by a mechanism involvingrecrystallization or crystal growth and oxidation of impurities andintermediates including FFCA. One of the functions of the secondaryoxidation zone is to convert FFCA to FDCA. FFCA is consideredmonofunctional relative to a polyester condensation reaction because itcontains only one carboxylic acid. FFCA is present in the carboxylicacid composition stream 110 and the low impurity slurry stream 210. FFCAis generated in the primary oxidation zone 125 because the reaction of5-HMF to FFCA can be about eight times faster than the reaction of FFCAto the desired di-functional product FDCA. Additional air or molecularoxygen may be fed in stream 320 to the secondary oxidation zone 335 inan amount necessary to oxidize a substantial portion of the partiallyoxidized products such as FFCA in the stream 210 to the correspondingcarboxylic acid FDCA. Generally, at least 70% by weight of the FFCApresent in the low impurity slurry stream 210 is converted to FDCA inthe secondary oxidation zone 335. Preferably, at least 80% by weight ofthe FFCA present in the low impurity slurry stream 210 is converted toFDCA in the secondary oxidation zone 335, and most preferably, at least90% by weight of the FFCA present in the low impurity slurry stream 210is converted to FDCA in the secondary oxidation zone 335. Significantconcentrations of monofunctional molecules like FFCA in the dried,purified FDCA product are particularly detrimental to polymerizationprocesses as they may act as chain terminators during the polyestercondensation reaction.

The amount of oxygen fed in the secondary oxidation zone 335 incontrolled to limit the burning of organic molecules to CO₂. The amountof oxygen in stream 330 is monitored and used to control the amount ofoxygen fed in stream 320. Another function of the secondary oxidationzone 335 is to dissolve and recrystallize solids present in the lowimpurity slurry stream 210 fed to the secondary oxidation zone. At least10% by weight, 25% by weight, 50% by weight, and preferably at least 85%by weight of solid impurities and oxidation by-products in stream 210feed to the secondary oxidation zone 335 go into solution as the FDCAparticles are dissolved and re-crystallized in the secondary oxidationzone 335. Off gas from the secondary oxidation zone is withdrawn vialine 330 and fed to a recovery system where the solvent is removed fromthe off gas comprising volatile organic compounds (VOCs). VOCs includingmethyl bromide may be treated, for example by incineration in acatalytic oxidation unit. The purified slurry stream 310 generated inthe secondary oxidation zone is routed to the crystallization zone 425.

Step (d) comprises crystallizing the secondary oxidation slurry 310 in acrystallization zone 425 to form a crystallized slurry stream 410.Generally, the crystallization zone 425 comprises at least onecrystallizer. Vapor from the crystallization zone can be condensed in atleast one condenser and returned to the crystallization zone 425 orrouted away from crystallization zone 425. Optionally, the liquid fromthe condenser or vapor product from the crystallization zone can berecycled, or it can be withdrawn or sent to an energy recovery device.In addition, the crystallizer off gas is removed via line 420 and can berouted to a recovery system where the solvent is removed, andcrystallizer off gas comprising VOCs may be treated, for example, byincineration in a catalytic oxidation unit. When the carboxylic acid isFDCA, the purified slurry stream 310 from the secondary oxidation zone335 is fed to a crystallization zone 425 comprising at least onecrystallizer where it is cooled to a temperature between about40.degrees C. to about 175 degrees C. to form a crystallized slurrystream 410, preferably to a temperature between about 50 degrees C. toabout 170 degrees C., and most preferably from about 60 degrees C. toabout 165 degrees C.

The crystallized slurry stream 410 is then routed to a cooling zone 430to generate a cooled crystallized slurry stream 510. The cooling of thecrystallized slurry stream 410 can be accomplished by any means known inthe art. Typically, the cooling zone 430 comprises a flash tank. Thetemperature of stream 510 can range from 35° C. to 160° C., 45° C. to120° C., and preferably from 55° C. to 95° C.

In another embodiment, a portion of up to 100% of the secondaryoxidation slurry stream 310 is routed directly to the cooling zone 425,thus the portion is not subjected to a crystallization zone 430. In yetanother embodiment, a portion of up to 100% of the crystallized slurrystream 410 is routed directly to a secondary liquid displacement zonewhich is not illustrated in FIG. 1. Up to 100% of the slurry effluentcomprising FDCA from a secondary liquid displacement zone can be routedto the solid-liquid separation zone 625 and or routed directly to thecooling zone 430. The function of the secondary liquid displacement zoneis to displace a portion of solvent in the crystallized slurry stream410 with fresh solvent and or water wherein a portion must be greaterthan 5 weight percent. The secondary liquid displacement zone isseparate and distinct from the liquid displacement zone 225 locatedafter the primary oxidation zone 125. The same type of equipment may beused for both the primary and secondary liquid displacement zones. Inyet another embodiment, crystallized slurry stream 410 can be routeddirectly to the solid-liquid separation zone 625 without being firstprocessed in the cooling zone 430.

Step (e) comprises isolating, washing, and dewatering solids present inthe cooled, crystallized slurry stream 510 in the solid-liquidseparation zone 625. These functions may be accomplished in a singlesolid-liquid separation device or multiple solid-liquid separationdevices. The solid-liquid separation zone 625 comprises at least onesolid-liquid separation device capable of separating solids and liquids,washing solids with a wash solvent stream 620, and reducing the %moisture in the washed solids to less than 30 weight %, less than 25weight %, less than 20 weight %, less than 15 weight %, and preferablyless than 10 weight %.

Equipment suitable for the solid liquid separation zone 625 cantypically be comprised of, but not limited to, the following types ofdevices: centrifuges, cyclones, rotary drum filter, belt filters,pressure leaf filters, candle filters, etc. The preferred solid liquidseparation device for the solid liquid separation zone 625 is a rotarypressure drum filter. The temperature of the cooled, crystallized slurrysteam 510 which is routed to the solid-liquid separation zone 625 canrange from 50° C. to 140° C., 70° C. to 120° C., and is preferably from75° C. to 95° C. The wash solvent stream 620 comprises a liquid suitablefor displacing and washing mother liquor from the solids.

In one embodiment of the invention, a suitable wash solvent comprisesacetic acid and water. In another embodiment, a suitable solventcomprises water up to 100% water. The temperature of the wash solventcan range from 20° C. to 135° C., 40° C. and 110° C., and preferablyfrom 50° C. to 90° C. The amount of wash solvent used is defined as thewash ratio and equals the mass of wash divided by the mass of solids ona batch or continuous basis. The wash ratio can range from about 0.3 toabout 5, about 0.4 to about 4, and preferably from about 0.5 to 3.

After solids are washed in the solid liquid separation zone, they aredewatered. Dewatering involves reducing the mass of moisture presentwith the solids to less than 30% by weight, less than 25% by weight,less than 20% by weight, less than 15% by weight, and most preferablyless than 10% by weight resulting in the generation of a purified wetcake stream 610. In one embodiment, dewatering is accomplished in afilter by passing a gas stream through the solids to displace freeliquid after the solids have been washed with a wash solvent. In anotherembodiment, dewatering is achieved by centrifugal forces in a perforatedbowl or solid bowl centrifuge. Stream 630 generated in the solid-liquidseparation zone 625 is a mother liquor stream comprising oxidationsolvent, catalyst, and some impurities and oxidation byproducts. In oneembodiment, a portion of stream 630 is routed to a purge zone 235 and aportion is routed back to the primary oxidation zone 125 wherein aportion is at least 5 weight %. Wash liquor stream 640 is also generatedin the solid-liquid separation zone 625 and comprises a portion of themother liquor present in stream 510 and wash solvent wherein the ratioof mother liquor mass to wash solvent mass is less than 3 and preferablyless than 2.

Step (f) comprises drying the purified wet cake stream 610 in a dryingzone 725 to generate a dry purified carboxylic acid 710 and a vaporstream 720. In one embodiment, vapor stream 720 comprises wash solventvapor. In another embodiment, vapor stream 720 comprises oxidationsolvent and wash solvent. The drying zone 725 comprises at least onedryer and can be accomplished by any means known in the art that iscapable of evaporating at least 10% of the volatiles remaining in thepurified wet cake stream 610 to produce the dried, purified carboxylicacid 710 comprising purified FDCA and a vapor stream 720. For example,indirect contact dryers include, but are not limited to, a rotary steamtube dryer, a Single Shaft Porcupine® dryer, and a Bepex Solidaire®dryer. Direct contact dryers include, but are not limited to, a fluidbed dryer and drying in a convey line can be used for drying to producestream 710. The dried, purified carboxylic acid 710 comprising purifiedFDCA can be a carboxylic acid composition with less than 8% moisture,preferably less than 5% moisture, and more preferably less than 1%moisture, and even more preferably less than 0.5%, and yet morepreferably less than 0.1%. In another embodiment of this invention, ifthe liquid portion of the purified wet cake stream 610 comprises waterand contains less than 0.1 weight % acetic acid, less than 500 ppm wtacetic acid, and preferably less than 200 ppm wt, the stream 610 can befed directly to a polymerization zone without first being dried.

In one embodiment of the invention, a vacuum system can be utilized todraw vapor stream 720 from the drying zone 725. If a vacuum system isused in this fashion, the pressure of stream 720 at the dryer outlet canrange from about 760 mmHg to about 400 mmHg, from about 760 mmHg toabout 600 mmHg, from about 760 mmHg to about 700 mmHg, from about 760mmHg to about 720 mmHg, and from about 760 mmHg to about 740 mmHgwherein pressure is measured in mmHg above absolute vacuum. The contentsof the conduit between solid-liquid separation zone 625 and drying zone725 utilized to transfer the purified wet cake stream 610 comprises wetcake stream and gas wherein gas is the continuous phase. The pressure atthe exit of the solid liquid separation zone 625 can be close to that ofthe pressure where vapor stream 720 exits the drying zone 725, whereinclose is defined as within 2 psig, within 0.8 psig, and preferablywithin 0.4 psig.

In an embodiment of the invention, the dried, purified carboxylic acid710 has a b* less than about 9.0. In another embodiment of theinvention, the b* color of the dried, purified carboxylic acid 710 isless than about 6.0. In another embodiment of the invention, the b*color of the dried, purified carboxylic acid 710 is less than about 5.0.In another embodiment of the invention, the b* color of the dried,purified carboxylic acid 710 is less than about 4.0. In anotherembodiment of the invention, the b* color of the dried, purifiedcarboxylic acid 710 is less than about 3. The b* color is one of thethree-color attributes measured on a spectroscopic reflectance-basedinstrument. A Hunter Ultrascan XE instrument in reflectance mode istypically the measuring device. Positive readings signify the degree ofyellow (or absorbance of blue), while negative readings signify thedegree of blue (or absorbance of yellow).

It should be appreciated that the process zones previously described canbe utilized in any other logical order to produce the dried, purifiedcarboxylic acid 710. It should also be appreciated that when the processzones are reordered that the process conditions may change. It is alsounderstood that all percent values are weight percents.

Step (g) is an optionally step comprising decolorizing the FDCA in thisprocess or an esterified FDCA with a diol stream via hydrogenation. Inone embodiment, the diol stream comprises ethylene glycol. In anotherembodiment, the diol stream comprises isomers of cyclohexane diol,preferably the 1-4 cyclohexane diol isomer. The decolorizing of the FDCAin this process or an esterified FDCA can be accomplished by any meansknown in the art and is not limited to hydrogenation. However, forexample, in one embodiment of the invention, the decolorizing can beaccomplished by reacting a carboxylic acid that has undergoneesterification treatment, for example with ethylene glycol, withmolecular hydrogen in the presence of a hydrogenation catalyst in areactor zone to produce a decolorized carboxylic acid solution or adecolorized ester product.

For the reactor zone, there are no special limitations in the form orconstruction thereof, subject to an arrangement that allows supply ofhydrogen to effect intimate contact of the carboxylic acid or esterproduct with the catalyst in the reactor zone. Typically, thehydrogenation catalyst is usually a single Group VIII metal orcombination of Group VIII metals. Preferably, the catalyst is selectedfrom a group consisting of palladium, ruthenium, rhodium and combinationthereof. The reactor zone comprises a hydrogenation reactor thatoperates at a temperature and pressure sufficient to hydrogenate aportion of the characteristically yellow compounds to colorlessderivatives.

Since numerous modifications and changes will readily occur to thoseskilled in the art, it is not desired to limit this invention to theexact process and operations illustrated and described above, andaccordingly all suitable modifications and equivalents may be resortedto, falling within the scope of the invention.

EXAMPLES

This invention can be further illustrated by the following examples ofembodiments thereof, although it will be understood that these examplesare included merely for the purposes of illustration and are notintended to limit the scope of the invention unless otherwisespecifically indicated.

Examples Set 1

In Examples 1a-3d, glacial acetic acid and the catalyst components inconcentrations described in Tables 1, 2 and 3 were transferred to a 300mL titanium autoclave equipped with a high pressure condenser, a baffleand an Isco pump. Cobalt, manganese and ionic bromine were provided ascobalt (II) acetate tetrahydrate, manganese (II) acetate and sodiumbromide and/or aqueous hydrobromic acid respectively. The autoclave waspressurized with approximately 50 psig of nitrogen and the homogeneousmixture was heated to the desired temperature in a closed system (i.e.,with no gas flow) with stirring. At reaction temperature, an air flow of1500 sccm was introduced at the bottom of the solution and the reactionpressure was adjusted to the desired pressure. A solution of5-HMF/5-AMF/5-EMF in acetic acid was fed to the mixture at a rate of0.833 mL/min via a high pressure Isco pump (this is t=0 for the reactiontime). After 30 seconds from the start of substrate feeding, 1.0 g ofperacetic acid in 5.0 mL of acetic acid was introduced using a blow-caseto start the reaction. The feed was stopped after 1 h and the reactioncontinued for an additional hour at the same conditions of air flow,temperature and pressure. After the reaction time was completed, the airflow was stopped and the autoclave was cooled to room temperature anddepressurized. The heterogeneous mixture was filtered to isolate thecrude FDCA. The mass of the filtrate was recorded. The crude FDCA waswashed with 60 mL of acetic acid two times and then twice with 100 mL ofDI water. The washed crude FDCA was oven dried at 110° C. under vacuumovernight and then weighed. The solid and the filtrate were analyzed byGas Chromatography using BSTFA derivatization method.

The Off-gas was analyzed for CO and CO₂ by ND-1R (ABB, Advanced Optima)and O₂ by a paramagnetism detection system (Servomex, 1440 Model).

Analytical

Gas Chromatographic Method

Process samples were analyzed using a Shimadzu gas chromatograph Model2010 (or equivalent) equipped with a split/heated injector (300° C.) anda flame ionization detector (300° C.). A capillary column (60 meter×0.32mm ID) coated with (6% cyanopropylphenyl)-methylpolysiloxane at 1.0 μmfilm thickness (such as DB-1301 or equivalent) was employed. Helium wasused as the carrier gas with an initial column head pressure of 29.5 psiand an initial column flow of 3.93 mL/minute while the carrier gaslinear velocity of 45 cm/second was maintained constant throughout theentire oven temperature program. The column temperature was programmedas follows: The initial oven temperature was set at 80° C. and was heldfor 6 minutes, the oven was ramped up to 150° C. at 4° C./minute and washeld at 150° C. for 0 minute, the oven was ramped up to 240° C. at 10°C./minute and was held at 240° C. for 5 minutes, then the oven wasramped up to 290° C. at 10° C./minute and was held at 290° C. for 17.5minutes (the total run time was 60 mins). 1.0-μl of the prepared samplesolution was injected with a split ratio of 40:1. EZ-Chrom Elitechromatography data system software was used for data acquisition anddata processing. The sample preparation was done by weighing 0.1 g(accurate to 0.1 mg) of sample in a GC vial and adding 200.0 μl ISTDsolution (1% by volume of decane in pyridine) and 1000 μl of BSTFA (N,O-bis(trimethylsilyl) trifluoroacetamide) with 1% TMSCl(trimethylchlorosilane) to the GC vial. The content was heated at 80° C.for 30 minutes to ensure complete derivatization. 1.0-μl of thisprepared sample solution was injected for GC analysis.

Color Measurement.

1) Assemble the Carver Press die as instructed in the directions—placethe die on the base and place the bottom 40 mm cylinder polished sideface-up.2) Place a 40 mm plastic cup (Chemplex Plasticup, 39.7×6.4 mm) into thedie.3) Fill the cup with the sample to be analyzed. The exact amount ofsample added is not important.4) Place the top 40 mm cylinder polished side face-down on the sample.5) Insert the plunger into the die. No “tilt” should be exhibited in theassembled die.6) Place the die into the Carver Press, making sure that it is near thecenter of the lower platen. Close the safety door.7) Raise the die until the upper platen makes contact with the plunger.Apply >20,000 lbs pressure. Then allow the die to remain under pressurefor approximately 3 minutes (exact time not critical).8) Release the pressure and lower the lower platen holding the die.9) Disassemble the die and remove the cup. Place the cup into a labeledplastic bag (Nasco Whirl-Pak 4 oz).10) Using a HunterLab Colorquest XE colorimeter, create the followingmethod (Hunterlab EasyQuest QC software, version 3.6.2 or later)

Mode: RSIN-LAV (Reflectance Specular Included-Large Area View)Measurements: CIE L* a* b* CIE X Y Z

11) Standardize the instrument as prompted by the software using thelight trap accessory and the certified white tile accessory pressedagainst the reflectance port.12) Run a green tile standard using the certified white tile and comparethe CIE X, Y, and Z values obtained against the certified values of thetile. The values obtained should be ±0.15 units on each scale of thestated values.13) Analyze the sample in the bag by pressing it against the reflectanceport and obtaining the spectrum and L*, a*, b* values. Obtain duplicatereadings and average the values for the report.

Interpretation of Results:

During the oxidation of 5-HMF to FDCA the alcohol site (ArCH₂OH) wasconverted into carboxylic acid (ArCOOH) mainly via aldehyde (ArCHO), eq3. Examples 1a, and 1b (Table-1) which use catalyst systems consistingof cobalt, manganese and aqueous hydrobromic acid source produced about90% yield of FDCA with >98% purity of crude FDCA solid and with a b* ofabout 6. The crude FDCA solid also contains 5-Formylfuran-2-carboxylicacid (FFCA), only the hydroxylmethyl groups are oxidized to carboxylicacid groups, due to incomplete oxidation.

Oxidation of 5-AMF, which contains an oxidizable ester and aldehydesmoieties, produced FDCA, FFCA, and acetic acid, eq 4. Examples 2a to 2b(Table-2) demonstrate that a minimum of 99% purity FDCA solid with a b*of about 7 or less can be achieved using cobalt, manganese and aqueoushydrobromic acid catalyst system.

Oxidation of 5-EMF, which contains an oxidizable ether and aldehydemoieties, produced FDCA, FFCA, 5-(ethoxycarbonyl)furan-2-carboxylic acid(EFCA) and acetic acid, eq 5. Examples 3a to 3d (Table-3) show that aminimum of 96% purity FDCA solid with a b* of about 6 or less can beachieved using cobalt, manganese and aqueous hydrobromic acid catalystsystem.

It is very important to note that in a continuous process under the sameconditions as described in this invention report (which was conducted asa batch process) even higher purity of crude FDCA is expected due toefficient mixing, relatively low concentrations of reactiveintermediates, and other reasons familiar to those skilled in the art.

TABLE 1 Results from semi-batch reactions performed as described aboveusing 5-HMF feed.* Mn conc Br conc Temp yield of FDCA yield of FFCASolid Composition Example Co conc (ppm) (ppm) (ppm) (° C.) (%) (%) FDCAFFCA b* 1a 2000 93.3 3000 132 89.4 0.58 99.20 0.81 5.845 1b 2000 93.33000 132 88.6 0.8 98.67 0.77 6.175 *P = 130 psig.

TABLE 2 Results from semi-batch reactions performed as described aboveusing 5-AMF feed.* Mn conc Br conc Temp yield of FDCA yield of FFCASolid Composition Example Co conc (ppm) (ppm) (ppm) (° C.) (%) (%) FDCAFFCA b* 2a 2500 116.8 2500 130 88.2 0.25 99.71 0.25 4.4 2b 2000 93.53000 130 90.2 0.16 99.44 0.16 6.8 *P = 130 psig.

TABLE 3 Results from semi-batch reactions performed as described aboveusing EMF feed.* Co conc Mn conc Br conc Temp yield of FDCA yield ofFFCA yield of EFCA Solid Composition Example (ppm) (ppm) (ppm) (° C.)(%) (%) (%) FDCA FFCA EFCA b* 3a 2500 116.8 2500 130 89.0 0.02 0.2399.04 0.02 0.02 3.97 3b 2500 116.8 2500 130 87.4 0.42 1.31 98.08 0.420.04 2.74 3c 2000 93.5 3000 130 88.0 0.09 0.43 99.20 0.09 0.05 5.845 3d2000 93.5 3000 105 86.0 2.92 1.40 96.22 2.90 0.15 0.98 *P = 130 psig.

Examples Set 2

Air oxidation of 5-HMF using cobalt, manganese and ionic brominecatalysts system in acetic acid solvent were conducted. After reactionthe heterogeneous mixture was filtered to isolate the crude FDCA. Thecrude FDCA was washed with acetic acid two times and then twice with DIwater. The washed crude FDCA was oven dried at 110° C. under vacuumovernight. The solid and the filtrate were analyzed by GasChromatography using BSTFA derivatization method. b* of the solid wasmeasured using a Hunter Ultrascan XE instrument. As shown in Table 4 wehave discovered conditions that to generate yields of FDCA up to 89.4%,b*<6, and low carbon burn (<0.0006 mol/min CO+CO₂)

TABLE 4 Results from semi-batch reactions.* Exam- Bromide Co conc Mnconc Br conc yield of yield of CO (total CO₂ (total CO_(x) pH, beforecolor ple source (ppm) (ppm) (ppm) FDCA (%) FFCA (%) mol) mol) (mol/min)reaction (b*) 4a solid NaBr 2000 93.3 3000 81.6 0.81 0.013 0.0780.000758 −0.12 13.91 4b solid NaBr 2000 93.3 3000 82.6 0.87 0.013 0.0920.000875 −0.12 14.14 4c aqueous HBr 2000 93.3 3000 89.4 0.58 0.003 0.0610.000533 −1.03 5.845 4d aqueous HBr 2000 93.3 3000 88.6 0.8 0.0037 0.0610.000539 −1.03 6.175 *P = 130 psig, CO_(x) (mol/min) = CO (mol/min) +CO2 (mol/min).

Examples set 3

In Examples 5a-5h, glacial acetic acid and the catalyst components inconcentrations described in Table-5 were transferred to a 300 mLtitanium autoclave equipped with a high pressure condenser, a baffle andan Isco pump. Cobalt, manganese and ionic bromine were provided ascobalt (II) acetate tetrahydrate, manganese (II) acetate and sodiumbromide and/or aqueous hydrobromic acid respectively. The autoclave waspressurized with approximately 50 psig of nitrogen and then thehomogeneous mixture was heated to the desired temperature in a closedsystem (i.e., with no gas flow) with stirring. At reaction temperature,an air flow of 1500 sccm was introduced at the bottom of the solutionand the reaction pressure was adjusted to the desired pressure. Asolution of 5-HMF in acetic acid was fed to the mixture at a rate of0.833 mL/min via a high pressure Isco pump (this is t=0 for the reactiontime). After 30 seconds from the start of 5-HMF feeding, 1.0 g ofperacetic acid in 5.0 mL of acetic acid was introduced using a blow-caseto start the reaction. The feed was stopped after 1 h and the reactioncontinued for 1 more hour at the same conditions of air flow,temperature and pressure. After the reaction time was completed the airflow was stopped and the autoclave was cooled to room temperature anddepressurized. The heterogeneous mixture was filtered to isolate thecrude FDCA. The mass of the filtrate was recorded. The crude FDCA waswashed with 60 mL of acetic acid two times and then twice with 100 mL ofDI water. The washed crude FDCA was oven dried at 110° C. under vacuumovernight and then weighed. The solid and the filtrate were analyzed byGas Chromatography using BSTFA derivatization method.

The Off-gas was analyzed for CO and CO₂ by ND-1R (ABB, Advanced Optima)and O₂ by a paramagnetism detection system (Servomex, 1440 Model).

Analytical

Gas Chromatographic Method

Process samples were analyzed using a Shimadzu gas chromatograph Model2010 (or equivalent) equipped with a split/heated injector (300° C.) anda flame ionization detector (300° C.). A capillary column (60 meter×0.32mm ID) coated with (6% cyanopropylphenyl)-methylpolysiloxane at 1.0 μmfilm thickness (such as DB-1301 or equivalent) was employed. Helium wasused as the carrier gas with an initial column head pressure of 29.5 psiand an initial column flow of 3.93 mL/minute while the carrier gaslinear velocity of 45 cm/second was maintained constant throughout theentire oven temperature program. The column temperature was programmedas follows: The initial oven temperature was set at 80° C. and was heldfor 6 minutes, the oven was ramped up to 150° C. at 4° C./minute and washeld at 150 for 0 minute, the oven was ramped up to 240° C. at 10°C./minute and was held at 240 for 5 minutes, then the oven was ramped upto 290° C. at 10° C./minute and was held at 290 for 17.5 minutes (thetotal run time was 60 mins). 1.0-μl of the prepared sample solution wasinjected with a split ratio of 40:1. EZ-Chrom Elite chromatography datasystem software was used for data acquisition and data processing. Thesample preparation was done by weighing 0.1 g (accurate to 0.1 mg) ofsample in a GC vial and adding 200.0 μl ISTD solution (1% by volume ofdecane in pyridine) and 1000 μl of BSTFA (N,O-bis(trimethylsilyl)trifluoroacetamide) with 1% TMSCl (trimethylchlorosilane) to the GCvial. The content was heated at 80° C. for 30 minutes to ensure completederivatization. 1.0-μl of this prepared sample solution was injected forGC analysis.

pH Measurement.

The electrode for determining non-aqueous pH and millivolts was a SchottN6480-eth series electrode. The LiCl/EtOH filling solution was replacedwith (Et)₄N⁺Br⁻/ethylene glycol. The electrode response was monitored byMulti-T 2.2 software through a Jensen Systems cdv-70 series Sensolabinterface box. The buffers (pH 4 and 7) were purchased from VWR, and the(Et)₄N⁺Br⁻/ethylene glycol filling solution was from Metrohm.

To perform the pH measurements, a non-aqueous electrode was initiallycalibrated using aqueous buffers of 4 and 7 allowing the electrode toequilibrate with each for two to three minutes before calibrating at therespective level. Once the electrode was calibrated within 97.5% of 59.2millivolts slope, the samples were portioned (−15 mL) into smaller vialswith mini-Teflon stir bars. The samples were then placed on a stirplate, and the electrode was lowered into the sample. The depth of theelectrode was set to where the sample covered about half of the junctionslide. Once the sample and electrode was ready, the sample was measuredfor non-aqueous pH over a period of three minutes. The time wassufficient for equilibration between the electrode and the sample.Between each sample measurement, the electrode was rinsed withMillipore-grade water and wiped with a Kimwipe. The results wererecorded in non-aqueous pH units. The millivolts results were alsorecorded.

Color Measurement.

1) Assemble the Carver Press die as instructed in the directions—placethe die on the base and place the bottom 40 mm cylinder polished sideface-up.2) Place a 40 mm plastic cup (Chemplex Plasticup, 39.7×6.4 mm) into thedie.3) Fill the cup with the sample to be analyzed. The exact amount ofsample added is not important.4) Place the top 40 mm cylinder polished side face-down on the sample.5) Insert the plunger into the die. No “tilt” should be exhibited in theassembled die.6) Place the die into the Carver Press, making sure that it is near thecenter of the lower platen. Close the safety door.7) Raise the die until the upper platen makes contact with the plunger.Apply >20,000 lbs pressure. Then allow the die to remain under pressurefor approximately 3 minutes (exact time not critical).8) Release the pressure and lower the lower platen holding the die.9) Disassemble the die and remove the cup. Place the cup into a labeledplastic bag (Nasco Whirl-Pak 4 oz).10) Using a HunterLab Colorquest XE colorimeter, create the followingmethod (Hunterlab EasyQuest QC software, version 3.6.2 or later)

Mode: RSIN-LAV (Reflectance Specular Included-Large Area View)Measurements: CIE L* a* b* CIE X Y Z

11) Standardize the instrument as prompted by the software using thelight trap accessory and the certified white tile accessory pressedagainst the reflectance port.12) Run a green tile standard using the certified white tile and comparethe CIE X, Y, and Z values obtained against the certified values of thetile. The values obtained should be ±0.15 units on each scale of thestated values.13) Analyze the sample in the bag by pressing it against the reflectanceport and obtaining the spectrum and L*, a*, b* values. Obtain duplicatereadings and average the values for the report.

Interpretation of Results:

Examples 5c, 5d, 5e and 5f (Table-5) which use catalyst systemsconsisting of cobalt, manganese and aqueous hydrobromic acid or aqueoushydrobromic acid and sodium bromide as a bromide source produced about90% yield of FDCA, minimum colored impurities (measured by b*) and aminimum level of CO and CO₂ (CO_(x), mol/min) in the off-gas. One of thereasons for the differences in activity between hydrobromide and sodiumbromide, in a single batch reaction, is due to faster oxidation of HBrby Mn(III), eq 6, than sodium bromide (it is about 22 times faster:Jiao, X. J.; Espenson, J. H. Inorg. Chem. 2000, 39, 1549). The activityof hydrobromic acid or sodium bromide reaction mediums can be increasedby addition of a strong Brønsted acid (such as triflic acid, HCl, etc.).

Mn(OAc)₃+2HBr→2HOAc+Mn(OAc)Br₂→Mn(OAc)₂+HBr₂  (6)

Comparative examples 5g and 5h show the inhibiting effect of excessmanganese. Therefore it is desirable to limit the amount of manganese,during the oxidation process, to achieve high yield of FDCA.

It is very important to note that in a continuous process under the sameconditions as described in this invention report (conducted as a batchprocess) higher than 90% yield of FDCA expected due to efficient supplyof oxygen and mixing.

TABLE 5 Results from semi-batch reactions performed as described above.*Co conc Mn conc Br conc yield of yield of CO (total CO₂ (total CO_(x)pH, before Example Bromide source (ppm) (ppm) (ppm) FDCA (%) FFCA (%)mol) mol) (mol/min) reaction color (b*) 5a solid NaBr 2000 93.3 300081.6 0.81 0.013 0.078 0.000758 −0.12 13.91 5b solid NaBr 2000 93.3 300082.6 0.87 0.013 0.092 0.000875 −0.12 14.14 5c aqueous HBr 2000 93.3 300089.4 0.58 0.003 0.061 0.000533 −1.03 5.845 5d aqueous HBr 2000 93.3 300088.6 0.8 0.0037 0.061 0.000539 −1.03 6.175 5e aqueous HBr + solid 200093.3 3000 91.7 0.96 0.008 0.07 0.000650 −0.63 8.185 NaBr 5f aqueousHBr + solid 2000 93.3 3000 90.2 0.87 0.008 0.072 0.000667 −0.63 7.95NaBr 5g aqueous HBr 2000 2000 3000 79.4 1.08 0.009 0.072 0.000675 −0.846.21 5h aqueous HBr 2000 2000 3000 80.5 1.32 0.009 0.071 0.000667 −0.846.31 *T = 132 C, P = 130 psig. CO_(x) (mol/min) = CO (mol/min) + CO₂(mol/min). FFCA = 5-Formylfuran-2-carboxylic acid.

Example Set 4

In Examples 1-34, 72, 73, 85, 86, 91, 92 and 93 glacial acetic acid andthe catalyst components in concentrations described in the Tables 6 and7 were transferred to a 300 mL titanium autoclave equipped with a highpressure condenser, a baffle and an Isco pump. Cobalt, manganese andionic bromine were provided as cobalt (II) acetate tetrahydrate,manganese (II) acetate and sodium bromide/aqueous hydrobromic acidrespectively. The autoclave was pressurized with approximately 50 psigof nitrogen and then the homogeneous mixture was heated to the desiredtemperature in a closed system (i.e., with no gas flow) with stirring.At reaction temperature, an air flow of 1500 sccm was introduced at thebottom of the solution and the reaction pressure was adjusted to thedesired pressure. A solution of 5-HMF in acetic acid was fed to themixture at a rate of 0.833 mL/min via a high pressure Isco pump (this ist=0 for the reaction time). After 30 seconds from the start of 5-HMFfeeding, 1.0 g of peracetic acid in 5.0 mL of acetic acid was introducedusing a blow-case to start the reaction. The feed was stopped after 1 hand the reaction continued for 1 more hour at the same conditions of airflow, temperature and pressure. After the reaction time was completedthe air flow was stopped and the autoclave was cooled to roomtemperature and depressurized. The heterogeneous mixture was filtered toisolate the crude FDCA. The mass of the filtrate was recorded. The crudeFDCA was washed with 60 mL of acetic acid two times and then twice with100 mL of DI water. The washed crude FDCA was oven dried at 110° C.under vacuum overnight and then weighed. The solid and the filtrate wereanalyzed by Gas Chromatography using BSTFA derivatization method. Atypical GC-chromatogram for isolated crude FDCA sample is shown in FIG.2. The purity of this solid was confirmed by NMR spectroscopy, FIGS. 3and 4.

The Off-gas was analyzed for CO and CO₂ by ND-1R (ABB, Advanced Optima)and O₂ by a paramagnetism detection system (Servomex, 1440 Model).

Analytical

Gas Chromatographic Method

Process sample was analyzed using a Shimadzu gas chromatograph Model2010 (or equivalent) equipped with a split/heated injector (300° C.) anda flame ionization detector (300° C.). A capillary column (60 meter×0.32mm ID) coated with (6% cyanopropylphenyl)-methylpolysiloxane at 1.0 μmfilm thickness (such as DB-1301 or equivalent) was employed. Helium wasused as the carrier gas with an initial column head pressure of 29.5 psiand an initial column flow of 3.93 ml/minute while the carrier gaslinear velocity of 45 cm/second was maintained constant throughout theentire oven temperature program. The column temperature was programmedas follows: The initial oven temperature was set at 80° C. and was heldfor 6 minutes, the oven was ramped up to 150° C. at 4° C./minute and washeld at 150 for 0 minute, the oven was ramped up to 240° C. at 10°C./minute and was held at 240 for 5 minute, then the oven was ramped upto 290° C. at 10° C./minute and was held at 290 for 17.5 minutes (thetotal run time was 60 mins). 1.0-μl of the prepared sample solution wasinjected with a split ratio of 40:1. EZ-Chrom Elite chromatography datasystem software was used for data acquisition and data processing. Thesample preparation was done by weighing 0.1 g (accurate to 0.1 mg) ofsample in a GC vial and adding 200.0 μl ISTD solution (1% by volume ofdecane in pyridine) and 1000 μl of BSTFA (N,O-bis(trimethylsilyl)trifluoroacetamide) with 1% TMSCl (trimethylchlorosilane) to the GCvial. The content was heated at 80° C. for 30 minutes to ensure completederivatization. 1.0-μl of this prepared sample solution was injected forGC analysis.

Interpretation of Results:

Experiments 1-34, Table 6, were conducted by varying temperature,pressure and levels of cobalt and bromine concentrations to determineoptimum conditions and catalyst compositions that produces very highyield of FDCA with minimum amount of carbon burn. In this invention, theweight ratio of cobalt to manganese was deliberately kept very high(i.e. 21) in all the reactions to avoid the inhibiting effect of excessmanganese especially below 160° C.

As can be seen from FIG. 5, under the reaction conditions investigatedin this invention the factor that has the most impact on the yield ofFDCA is temperature. It is also important to note that the yieldincreases with increasing cobalt and bromine concentrations.

The data presented in Table 6 was used to develop a theoreticalpolynomial model to predict FDCA yield under different conditions, eq-7.Examples of predicted FDCA yields using this model is given in Table 7.Experiments No 72, 73, 85, and 86, Table 7, were conducted under thepredicted conditions. As can be seen from the results they agree wellwith the predicted values within experimental error.

% yield of FDCA=−91.469+2.83*T−0.01*P−0.02*[Co]+0.003*[Br]−0.01*T²+3.9*10⁻⁶*[Co]²  (7)

Examples 91-93, Table 8, were conducted under the US patent applications(US200310055271 A1) conditions using our set-up. As can be seen fromTables 6, 7 and 8, the patent application conditions gave much inferioryield of FDCA than the current invention.

TABLE 6 Results from semi-batch reactions performed as described above.*C: Cobalt D:Br A: Temperature B: Pressure Conc Conc % % yield of % yieldof CO CO2 CO_(x) Run deg, C. psi ppm ppm conversion FDCA FFCA (totalmol) (total mol) (mol/min) 1 130 200 4000 1500 99.26 75.7 1.1 0.0110.088 0.00083 2 155 450 3000 2250 99.1 67.3 0.08 0.032 0.163 0.00163 3180 200 4000 3000 100 68.7 0.037 0.049 0.161 0.00175 4 180 700 2000 300098.57 57.3 0.0049 0.044 0.17 0.00178 5 180 200 2000 1500 94.47 48.3 0.960.044 0.125 0.00141 6 155 450 3000 2250 99.07 67.2 0.07 0.031 0.1580.00158 7 130 700 4000 3000 100 78 0.34 0.017 0.183 0.00167 8 130 2002000 3000 97.11 82.1 1.1 0.012 0.095 0.00089 9 180 700 4000 1500 99.5 530.02 0.053 0.148 0.00168 10 155 450 3000 2250 99.38 70.9 0.148 0.0320.16 0.00160 11 130 700 2000 1500 99.84 68 0.79 0.024 0.168 0.00160 12180 200 4000 1500 99.26 53.3 0.003 0.061 0.185 0.00205 13 155 450 30002250 100 70 0.2 0.03 0.158 0.00157 14 130 200 2000 1500 96.2 74.6 1.490.015 0.093 0.00090 15 130 200 4000 3000 99.57 85.3 0.7 0.009 0.0830.00077 16 130 700 4000 1500 99.9 73.9 0.87 0.018 0.129 0.00123 17 155450 3000 2250 100 71.2 0.1 0.03 0.159 0.00158 18 130 700 2000 3000 99.8970.3 0.54 0.02 0.13 0.00125 19 180 200 2000 3000 99.5 58.4 0.464 0.0580.0193 0.00064 20 180 700 2000 1500 100 54.3 0.55 0.053 0.175 0.00190 21155 450 3000 2250 100 58.5 0.089 0.029 0.155 0.00153 22 180 700 40003000 100 60 0.025 0.048 0.158 0.00172 23 200 450 3000 2250 100 23 00.158 0.284 0.00368 24 200 450 3000 2250 100 23.8 0 0.156 0.266 0.0035225 155 450 3000 2250 99.69 66.2 0.143 0.028 0.154 0.00152 26 155 50 30002250 99.05 79 0.075 0.019 0.109 0.00107 27 155 450 3000 1500 98.14 67.40.18 0.032 0.15 0.00152 28 155 950 3000 2250 99.94 62.8 0.118 0.0340.164 0.00165 29 155 450 3000 2250 99.81 68.9 0.093 0.027 0.152 0.0014930 105 450 3000 2250 97.12 66.9 3.56 0.013 0.099 0.00093 31 155 450 40002250 99.92 66.4 0.06 0.032 0.158 0.00158 32 155 450 3000 3750 100 68.80.178 0.026 0.151 0.00148 33 155 450 3000 2250 99.76 72 0.1 0.027 0.1540.00151 34 155 450 2000 2250 99.89 70.3 0.54 0.02 0.13 0.00125 *Cobaltto manganese weight ratio = 21 for all experiments

TABLE 7 Predicted yields of FDCA. 72, 73, 74, 85 and 86 are experimentalresults.* Temper- Cobalt Br yield of yield of Number ature Pressure ConcConc FDCA FFCA 35 139 50 3999 3000 85.1504 0.447749 36 139 50 4000 298185.0945 0.442835 37 138 70 4000 3000 85.0502 0.469564 38 138 74 40003000 85.0244 0.473723 39 138 63 3988 3000 84.9913 0.463436 40 139 503999 2948 84.976 0.435265 41 139 50 4000 2938 84.9472 0.432597 42 139 503981 2973 84.9129 0.443582 43 138 51 3951 2999 84.7494 0.455411 44 13850 3935 2999 84.629 0.455856 45 138 50 3917 3000 84.4874 0.458526 46 13853 3917 3000 84.4716 0.461423 47 138 50 4000 2777 84.3976 0.406641 48138 50 3905 2998 84.3893 0.45981 49 137 50 3881 3000 84.2031 0.463274 50139 50 3886 3000 84.1187 0.428238 51 137 50 4000 2596 83.7624 0.39589752 137 50 3992 2606 83.724 0.39788 53 136 50 3804 3000 83.6075 0.47355554 136 51 3780 3000 83.4262 0.477259 55 137 227 3994 3000 83.39110.433817 56 137 50 4000 2386 82.9936 0.394841 57 135 50 3694 294682.6042 0.479136 58 135 50 4000 2166 82.2022 0.446345 59 136 50 40002152 82.1354 0.433632 60 131 61 2000 3000 81.8774 1.49331 61 131 59 20022993 81.8506 1.4836 62 131 59 2000 2986 81.8418 1.48296 63 131 55 20263000 81.7822 1.4441 64 130 83 2000 3000 81.5573 1.48713 65 132 50 20743000 81.5533 1.34737 66 130 91 2000 3000 81.4703 1.47787 67 130 89 20003000 81.4632 1.4882 68 132 50 2103 3000 81.3982 1.28915 69 131 50 20052833 81.2848 1.37298 70 139 51 4000 1973 81.2207 0.327309 71 132 1302000 3000 81.1875 1.33938  72. 132 130 2000 3000 81.5 0.79 Experimentalresult.*  73. 132 130 2000 3000 81.6 0.81 Experimental result.*  74. 132130 2000 3000 81.6 0.81 Experimental result.* 75 132 50 2144 300081.1813 1.21129 76 131 50 2146 2993 81.1115 1.22154 77 132 50 2160 300081.1035 1.18214 78 132 50 2001 2739 81.0004 1.30911 79 132 50 2000 268180.7904 1.28011 80 133 50 2228 2993 80.7581 1.06473 81 133 52 2000 256380.3266 1.22742 82 133 50 2000 2484 80.0491 1.2075 83 130 51 3136 300079.8341 0.591352 84 133 50 4000 1542 79.8127 0.750216 85 135 50 30663000 79.7967 0.503153  85. 135 50 3066 3000 85.3 0.86 Experimentalresult.*  86. 135 50 3066 3000 83.2 0.96 Experimental result.* 87 134 504000 1527 79.7531 0.668935 88 135 206 2262 3000 78.9815 0.792438 89 13250 2000 2052 78.3528 1.25619 90 137 627 2000 3000 75.8366 0.489432*Cobalt to Manganese weight ratio = 21 for all experiments.

TABLE 8 Reactions conducted using the patent application(US20030055271A1) conditions.^(a) C: Cobalt D: Br % % yield of % yieldof CO CO2 (total CO_(x) Run A: Temperature B: Pressure Conc Concconversion FDCA FFCA (total mol) mol) (mol/min) patent 125 950 406 110244.7 2.4 (US2003/ 0055271A1) 91^(b) 125 950 406 1102 98.42 40.1 2.3 0.030.128 0.00132 patent 100 950 406 1102 44.8 3.3 (US2003/ 0055271A1)92^(b) 100 950 406 1102 60.51 0.5 4.4 0.005 0.028 0.00028 93^(b) 100 950406 1102 64.33 0.9 2.7 0.005 0.031 0.00030 ^(a)Cobalt to Manganese ratio= 1. ^(b)Unknown peaks in the GC.

Examples Set 5

In Examples 9a-11b, glacial acetic acid and the catalyst components inconcentrations described in Tables 9, 10 and 11 were transferred to a300 mL titanium autoclave equipped with a high pressure condenser, abaffle and an Isco pump. Cobalt, manganese and ionic bromine wereprovided as cobalt (II) acetate tetrahydrate, manganese (II) acetate andaqueous hydrobromic acid respectively. The autoclave was pressurizedwith approximately 50 psig of nitrogen and the homogeneous mixture washeated to the desired temperature in a closed system (i.e., with no gasflow) with stirring. At reaction temperature, an air flow of 1500 sccmwas introduced at the bottom of the solution and the reaction pressurewas adjusted to the desired pressure. A solution of 5-MF/5-AMF/5-EMF inacetic acid was fed to the mixture at a rate of 0.833 mL/min via a highpressure Isco pump (this is t=0 for the reaction time). After 30 secondsfrom the start of substrate feeding, 1.0 g of peracetic acid in 5.0 mLof acetic acid was introduced using a blow-case to start the reaction.The feed was stopped after 1 h and the reaction continued for anadditional hour at the same conditions of air flow, temperature andpressure. After the reaction time was completed, the air flow wasstopped and the autoclave was cooled to room temperature anddepressurized. The heterogeneous mixture was filtered to isolate thecrude FDCA. The mass of the filtrate was recorded. The crude FDCA waswashed with 60 mL of acetic acid two times and then twice with 100 mL ofDI water. The washed crude FDCA was oven dried at 110° C. under vacuumovernight and then weighed. The solid and the filtrate were analyzed byGas Chromatography using BSTFA derivatization method.

The off-gas was analyzed for CO and CO₂ by ND-1R (ABB, Advanced Optima)and O₂ by a paramagnetism detection system (Servomex, 1440 Model).

Analytical

Gas Chromatographic Method

Process samples were analyzed using a Shimadzu gas chromatograph Model2010 (or equivalent) equipped with a split/heated injector (300° C.) anda flame ionization detector (300° C.). A capillary column (60 meter×0.32mm ID) coated with (6% cyanopropylphenyl)-methylpolysiloxane at 1.0 μmfilm thickness (such as DB-1301 or equivalent) was employed. Helium wasused as the carrier gas with an initial column head pressure of 29.5 psiand an initial column flow of 3.93 mL/minute while the carrier gaslinear velocity of 45 cm/second was maintained constant throughout theentire oven temperature program. The column temperature was programmedas follows: The initial oven temperature was set at 80° C. and was heldfor 6 minutes, the oven was ramped up to 150° C. at 4° C./minute and washeld at 150° C. for 0 minute, the oven was ramped up to 240° C. at 10°C./minute and was held at 240° C. for 5 minutes, then the oven wasramped up to 290° C. at 10° C./minute and was held at 290° C. for 17.5minutes (the total run time was 60 mins). 1.0-μl of the prepared samplesolution was injected with a split ratio of 40:1. EZ-Chrom Elitechromatography data system software was used for data acquisition anddata processing. The sample preparation was done by weighing 0.1 g(accurate to 0.1 mg) of sample in a GC vial and adding 200.0 μl ISTDsolution (1% by volume of decane in pyridine) and 1000 μl of BSTFA(N,O-bis(trimethylsilyl) trifluoroacetamide) with 1% TMSCl(trimethylchlorosilane) to the GC vial. The content was heated at 80° C.for 30 minutes to ensure complete derivatization. 1.0-μl of thisprepared sample solution was injected for GC analysis.

Interpretation of Results: 5-AMF Feed Studies:

Oxidation of 5-AMF, which contains an oxidizable ester and aldehydesmoieties, produced FDCA, FFCA, and acetic acid, eq 8. Experiments 9a-9k,Table 9, were conducted by varying temperature, and levels of cobalt andbromine concentrations to determine optimum conditions and catalystcompositions that produces very high yield of FDCA with minimum amountof carbon burn. In this invention, the weight ratio of cobalt tomanganese was deliberately kept very high (i.e. 21) in all the reactionsto avoid the inhibiting effect of excess manganese especially below 160°C. Further discussion on mechanism of initiation and inhibition byMn(II) in oxidation can be found in Zakharov, I. V. Kinetics andCatalysis 1998, 39, 485; and Jiao, X. J.; Espenson, J. H. Inorg. Chem.2000, 39, 1549.

TABLE 9 Results from semi-batch reactions performed as described aboveusing 5-AMF feed.* Factor 3 Response Response Factor 1 Factor 2 CobaltFactor 4 1 2 Temperature Pressure conc Br conc % yield of % yield of Run(° C.) (psig) (ppmw) (ppmw) FDCA FFCA 9a 180 130 2500 2500 44.6 0.25 9b130 130 2500 2500 88.2 0.25 9c 155 130 2000 3000 67.6 0.026 9d 130 1302000 3000 90.2 0.16 9e 155 130 2500 2500 64.52 0.35 9f 180 130 2000 300049.5 0.15 9g 105 130 2000 3000 64.8 1.8 9h 180 130 2000 3000 42.3 0.0079i 180 130 2500 2500 40.9 0.06 9j 130 130 2000 3000 86.9 0.79 9k 130 1302500 2500 88.5 0.71 *Cobalt to Manganese weight ratio = 21 for allexperiments

As can be seen from FIG. 6, under the reaction conditions investigated,in this invention, the factor that has the most impact on the yield ofFDCA is temperature. It is also important to note that the yield canincrease with increasing cobalt and bromine concentrations.

It is important to note that the same yield and selectivity can beobtained with mixed 5-HMF and 5-AMF feed-stocks with varying ratios ofthe two components.

5-EMF Feed Study:

Oxidation of 5-EMF, which contains an oxidizable ether and aldehydemoieties, produced FDCA, FFCA, 5-(ethoxycarbonyl)furan-2-carboxylic acid(EFCA) and acetic acid, eq 9.

Experiments 10a-10k, Table 10, were conducted by varying temperature,and levels of cobalt and bromine concentrations to determine optimumconditions and catalyst compositions that produces very high yield ofFDCA with minimum amount of carbon burn. Similar to the 5-AMF oxidationdescribed above the weight ratio of cobalt to manganese was deliberatelykept very high (i.e. 21) in all the reactions to avoid the inhibitingeffect of excess manganese especially below 160° C.

TABLE 10 Results from semi-batch reactions performed as described aboveusing 5-EMF feed.* Factor 3 Factor 1 Factor 2 Cobalt Factor 4 Response 1Response 2 Response 3 Temperature Pressure conc Br conc % yield of %yield of % yield of Run (° C.) (psig) (ppmw) (ppmw) FDCA FFCA EFCA 10a180 130 2500 2500 52.3 0.031 0.117 10b 130 130 2500 2500 88.8 0.02 0.22510c 155 130 2000 3000 57.5 0.058 0.28 10d 130 130 2000 3000 87.97 0.090.43 10e 155 130 2500 2500 64.52 0.35 0.47 10f 180 130 2000 3000 49.50.15 0.23 10g 105 130 2000 3000 86 2.92 1.4 10h 180 130 2000 3000 50.90.096 0.24 10i 180 130 2500 2500 48.9 0.4 0.61 10j 130 130 2000 300087.5 0.4 1.22 10k 130 130 2500 2500 87.4 0.42 1.3 *Cobalt to Manganeseweight ratio = 21 for all experiments

As can be seen from FIG. 7, under the reaction conditions investigatedin this invention the factor that has the most impact on the yield ofFDCA is temperature. It is important to note that the same yield andselectivity can be obtained with mixed 5-HMF and 5-EMF feed-stocks withvarying ratios of the two components.

5-MF Feed Study:

Oxidation of 5-MF, which contains an oxidizable methyl andaldehydesmoieties, produced FDCA, and FFCA eq 10. Experiments 11a and11b, Table 11, demonstrate that moderate yield of FDCA with high puritycan be obtained using 5-MF as a feed stock.

TABLE 11 Results from semi-batch reactions performed as described aboveusing 5-MF feed.* Factor 2 Factor 3 Factor 4 Factor 1 Pressure CobaltConc Br Conc Response 2 Response 3 Temperature (psig) (ppmw) (ppmw)Response 1 % yield of % yield of Run (° C.) psi ppm ppm % conversionFDCA FFCA 11a 130 130 2000 3000 100 61.3 0.082 11b 130 400 2500 2500 10061.8 0.083 *Cobalt to Manganese weight ratio = 21.

It is very important to note that in a continuous process under the sameconditions as described in this invention report (which was conducted asa batch process) with different feed stock even higher yields of crudeFDCA is expected due to efficient mixing, relatively low concentrationsof reactive intermediates, and other reasons familiar to those skilledin the art.

Claims not Limited to Disclosed Embodiments

The preferred forms of the invention described above are to be used asillustration only, and should not be used in a limiting sense tointerpret the scope of the present invention. Modifications to theexemplary embodiments, set forth above, could be readily made by thoseskilled in the art without departing from the spirit of the presentinvention.

The inventors hereby state their intent to rely on the Doctrine ofEquivalents to determine and assess the reasonably fair scope of thepresent invention as it pertains to any apparatus not materiallydeparting from but outside the literal scope of the invention as setforth in the following claims.

1. A carboxylic acid composition comprising: (a) furan-2,5-dicarboxylic acid in an amount greater than 90 weight percent; (b) b* value less than 20; and (c) FFCA in a range of from about 0.1 to about 4.0 weight percent (d) EFCA in an amount from 0.1 to 4 wt %.
 2. A carboxylic acid composition according to claim 1 where said furan-2,5-dicarboxylic acid is in an amount greater than 92 weight percent.
 3. A carboxylic acid composition according to claim 2 wherein said carboxylic acid composition has a b* value less than
 10. 4. A carboxylic acid composition according to claim 2 wherein said carboxylic acid composition has a b* value less than
 5. 5. A carboxylic acid composition according to claim 1 where said furan-2,5-dicarboxylic acid is in an amount greater than 94 weight percent.
 6. A carboxylic acid composition according to claim 5 wherein said carboxylic acid composition has a b* value less than
 10. 7. A carboxylic acid composition according to claim 5 wherein said carboxylic acid composition has a b* value less than
 5. 8. A carboxylic acid composition according to claim 1 where said furan-2,5-dicarboxylic acid is in an amount greater than 96 weight percent.
 9. A carboxylic acid composition according to claim 8 wherein said carboxylic acid composition has a b* value less than
 10. 10. A carboxylic acid composition according to claim 10 wherein said carboxylic acid composition has a b* value less than
 5. 11. A carboxylic acid composition according to claim 1 where said furan-2,5-dicarboxylic acid is in an amount greater than 98 weight percent.
 12. A furan-2,5-dicarboxylic acid (FDCA) composition produced by a process comprising: (a) oxidizing in a primary oxidation zone at least one oxidizable compound in an oxidizable raw material stream comprising EMF and MHF in the presence of a solvent stream comprising a saturated organic acid solvent having from 2-6 carbon atoms and a catalyst system at a temperature of about 100° C. to about 220° C. to produce a carboxylic acid composition; wherein said carboxylic acid composition comprises FDCA; wherein said primary oxidation zone comprises at least one oxidation reactor and wherein said catalyst system comprises cobalt in a range from about 500 ppm by weight to about 6000 ppm by weight with respect to the weight of the liquid in the primary oxidation zone, manganese in an amount ranging from about 2 ppm by weight to about 600 ppm by weight with respect to the weight of the liquid in the primary oxidation zone and bromine in an amount ranging from about 300 ppm by weight to about 4500 ppm by weight with respect to the weight of the liquid in the primary oxidation zone; (b) purifying said carboxylic acid composition to produce a dried purified carboxylic acid composition; wherein said purifying comprises a crystallization step, a filtering step and a drying step; wherein said dried purified carboxylic acid composition has a b* value less than
 20. 13. A composition according to claim 12 wherein said oxidation reactor comprises a bubble column.
 14. A composition according to claim 12 wherein said catalyst system comprises cobalt in a range from about 700 ppm to about 4500 ppm by weight with respect to the weight of the liquid in the primary oxidation zone, manganese in an amount ranging from about 20 ppm by weight to about 400 ppm by weight with respect to the weight of the liquid in the primary oxidation zone and bromine in an amount ranging from about 700 ppm by weight to about 4000 ppm by weight with respect to the weight of the liquid in the primary oxidation zone. 